1. Field of the Invention
This invention relates to an automatic article working system, and more particularly to an automatic article working system suitable for limited production of a variety of articles.
2. Description of the Prior Art
The automatic article working systems which have heretofore been used are generally suitable for the mass production of one kind of article in a stationary flow. In these systems, articles to be worked are automatically conveyed by means of special purpose conveyor means and measuring means to the machine tools located in a predetermined sequence of working steps.
Such automatic article working systems are, however, not suitable for limited production of a variety of articles.
Specifically, the prior art systems are not suitable when the articles to be worked have various shapes and are allowed to flow on the production line, and so the flow of articles to be worked is not constant. The special purpose machine tools and the conveying facilities do not have working and conveying functions suitable for the articles which have different configurations or shapes.
The diversification of the shapes of articles to be worked and the path through which articles to be worked travel requires general purpose machine tools and conveying means. Under such conditions, automatic working devices are required to prevent a decline of the rate of operation of the system. The line production system can be considered as one of the solutions thereof. In this system, according to PQ analysis and G.T technique, the kinds of articles to be worked are reduced as far as possible, and articles to be worked having similar shapes and sizes are selected and worked in principle by a predetermined series of machines located in the sequence of work steps in accordance with a predetermined tact time of one to one.
However, the kinds of articles to be automatically worked by such a line production system are limited. With an increase in the kinds of articles to be worked, many problems have occurred, and even when machine tools are automated, most of the conveying steps unavoidably depend on manpower.
For this reason, following automatic article working system suitable for limited production of a variety of articles is contemplated at present. Conveying facilities of a general purpose type such as conveyors, chutes and manipulators, etc. are arranged between N. C general purpose machine tools and automatic article working systems, etc. and one piece of the articles to be worked is loaded on a pallet or a truck and then transferred. Further, for the purpose of controlling work steps, waiting lines for articles to be worked and corresponding branch and joining means are provided along the conveying path. However, this system is disadvantageous in that, because only one piece is loaded on a pallet or a truck and conveyed individually, a large number of pallets or trucks are required, so that loading and unloading steps of the articles to be worked increase. Further, work step control is required by the one piece, and it is necessary to use a computer having a large capacity for this small operation. Furthermore, in order to control various kinds of articles to be worked requiring different work steps, it is necessary to provide a waiting line for subsequent work steps, and due to the branch and joining means for selectively feeding articles to be worked into work steps, large facilities and floor space are required, and the running cost thereof increases.